Earlier work has shown that calcium hexaboride can be subjected to temperatures and pressures to produce a sintered product. This product required temperatures around 1,600.degree. C and above if it was to achieve a density that approached the theoretical density for calcium hexaboride. It is desirable for certain purposes to produce the material with a density that is as high as possible. it is also desirable to produce this high density material at temperatures that are as low as possible. This latter aspect is primarily one of economics in that lower operating temperatures prolong the life of the vacuum hot-press equipment employed in the process as well as avoiding the necessity for constructing equipment having exceptional structural and insulating qualities. The sintered calcium hexaboride has utility as the principal ingredient of personnel armor and similar equipment that is designed to protect from shrapnel and similar fragmentary missiles.
The present invention, which has been designated, "reaction-hot-pressing," relates to a method for the fabrication of high density calcium hexaboride at temperatures below those of the prior art. The reaction-hot-pressing process comprises an in situ reaction of calcium oxide and amorphous boron to form the boride while simultaneously applying heat and pressure to the reaction to cause the sintering of the product as it is produced.
It is an object of the present invention to provide and disclose an improved method for the production of high density CaB.sub.6.
It is a further object of the present invention to provide and disclose an improved method for the production of high density CaB.sub.6 utilizing calcium oxide and amorphous boron as the starting ingredients.
It is a further object of the present invention to provide and disclose an improved method for the production of high density CaB.sub.6 from calcium oxide and amorphous boron utilizing subconventional hot pressing temperatures.